how to do Conditional Logic for early bird price?

Hi, how to do Conditional Logic for below scenario?
user first need to enter quantity of participant:
if quantity 1, then one fields for name, email, contact, company will appear
but if quantity 3, then user able to add all above fields for each participant

1) early bird price (price valid only until 7th june), with 2 different pricing:
if buy 1 equal $xxx
if buy 3 equal $yyy

2) after 7th june, can the form auto change the price into :
if buy 1 equal $zzz
if buy 3 equal $aaa

Please help.